Printing processes are becoming ever more important in the production of electronic components. Especially the printing of substrates for organic light emitting diodes (OLEDs), with regard to different OLED designs, is an area having high potential for reducing costs and for increasing the flexibility of production.
A conventional OLED substrate includes above a substrate electrical busbars and an internal extraction layer (IEL). An anode and a cathode with an organic functional layer system between the anode and cathode are formed above the substrate. The organic functional layer system may include one or a plurality of emitter layer(s) in which electromagnetic radiation is generated, one or a plurality of charge generating layer structure(s) each composed of two or more charge generating layers (CGL) for charge generation, and one or a plurality of electron blocking layers, also designated as hole transport layer(s) (HTL), and one or a plurality of hole blocking layers, also designated as electron transport layer(s) (ETL), in order to direct the current flow.
Conventionally, the electrical busbars are deposited on the anode or incorporated in the substrate. The production of incorporated electrical busbars in the substrate is relatively complex and inflexible with regard to different OLED designs.
Material of the further layers above the carrier accumulates at the electrical busbars, said material being applied in further wet coatings above the carrier. Furthermore, elevated electrical busbars entail the risk of short circuits on account of layer thickness inhomogeneities in the electrically functional layers deposited thereabove, that is to say the anode, cathode and the organic functional layer system. Elevated electrical busbars therefore conventionally require a laterally structured insulating coating—which is complex to process—for planarization, for example with a photoresist.